Drivers cross the Interstate 5 temporary bridge over the Skagit River that re-opened Wednesday in Burlington, Wash. The I-5 temporary bridge is open to all traffic except oversized and overweight loads, which are required to exit south bound I-5 at the George Hopper Road interchange at exit 229. A section of the Skagit River bridge collapsed May 23 when it was struck by a truck with an oversize load. (ASSOCIATED PRESS / The Skagit Valley Herald, Scott Terrell)

MOUNT VERNON, Wash. (AP) — Cars and trucks are rolling again across the Interstate 5 Skagit River bridge, restoring the traffic flow on the main route between Seattle and Vancouver, British Columbia.

A temporary span opened Wednesday morning, replacing a section of the bridge that collapsed May 23 when it was struck by a truck with an oversize load.

Workers with the state Department of Transportation and contractors rushed work on the temporary span to relieve drivers who lined up to detour through Mount Vernon and Burlington. The bridge carries 71,000 vehicles a day.

Those vehicles are back on the freeway, but they’ll be slowed at the bridge where the speed is reduced to 40 mph because of narrow lanes on the 160-foot temporary section. It carries two 11-foot lanes in each direction. Oversized and overweight loads will still be detoured.

The temporary bridge pieces were supplied by Acrow Bridge through an emergency contract the Transportation Department signed with Atkinson Construction. The Max Kuney construction company of Spokane was selected Tuesday for a permanent replacement this fall.

The temporary span and replacement cost nearly $18 million. The federal Transportation Department is paying for all but about $1 million of the work.

Despite all the work, the 58-year-old bridge is still rated as “functionally obsolete” because it was not designed to handle today’s traffic volume and big trucks. It’s also “fracture critical,” meaning that if a single, vital component is compromised, the bridge can crumple again.

In the accident last month, the driver of the oversized truck felt crowded by another southbound semi-truck on the bridge and the load struck a girder, causing one section of the bridge to fall, a preliminary National Transportation Safety Board report said. A final NTSB report on the cause of the bridge failure is likely months away.

A car and pickup truck went into the water and three people were rescued. Washington State Patrol Trooper Sean O’Connell was killed May 31 when his motorcycle collided with a truck while he was directing detoured traffic in Conway.